InputItem: php8.1 deprecated warning-Added returnTypeWillChange to offsetGet

src/Pecee/Http/Input/InputItem.php

@@ -89,6 +89,7 @@ class InputItem implements ArrayAccess, IInputItem, IteratorAggregate
         return isset($this->value[$offset]);
     }
 
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset): ?self
     {
         if ($this->offsetExists($offset) === true) {